There are so many of them. I have a huge, long list of favorites saved, but there are a few that I check all day long.
Love this - they typically have one deal a day, tending toward the electronics, but not always. Once in a while, they have a "woot off" day - and the deals change as they sell out. The best part sometimes is just to read the comment section.
Woot recently started an off-shoot for just kid stuff, which I love. I've gotten a couple things from there, including a great Thomas beginner set for way below the prices I had seen anywhere.
Major site that most shoppers know about already, but just in case...
People post deals and the hottest ones move up to the front page.
Blog by a woman names Collin, who posts all day, every day, with the best deal scenarios. Great for checking before you go to Target, Walmart, CVS, Walgreens! She also posts links to other great coupons, fun freebies, and other deals. She started doing a "Follow me" video segment every week, and is so freaking adorable. You'll love her even more!
http://www.mamabargains.com/ and http://www.babysteals.com/
Both post deals for moms and kids - shoes, toys, maternity wear, slings, strollers, etc. Everything a mom or dad could want! Babysteals posts one per day and mamabargains posts new items when one is sold out.
http://www.shnoop.com/ & http://www.cowboom.com/
Similar to woot above - a deal a day! Shnoop has a new one every day, but you can also get yesterday's deal if it's still available.
http://www.ruelala.com/ & http://www.hautelook.com/ & http://www.theminisocial.com/ & http://www.onekingslane.com/
These are all "invite-only sites" which are pretty easy to get "invited" to -- and they all have various deals going on. Ruelala and HauteLook are mostly designer-wear at major discounts. Sometimes they have home and kid stuff. MiniSocial has kid stuff - clothes, shoes, toys. OneKingsLane has all house stuff at great discounts (although sometimes it's still sky high b/c it's designer).
If you have a kindle, this is a great site to visit. They have a thread for free books and a thread for bargain books, that is usually updated daily by posts from avid readers. There are also quite a number of up and coming authors on here, which is very cool.
These are the sites I visit daily (and sometimes many times a day) to score some amazing deals. I can't tell you how much money I've saved using coupons that I wouldn't have been aware of otherwise. I also was made aware of some great sales and deals that really helped me with gift and Christmas shopping. Plus, they're fun to read for the most part!